The present invention relates to improvements in the art of separating suspending solids from liquids, and more particularly to an apparatus for purifying or clarifying liquids containing solids, contaminants, and the like.
It has been the heretofore practice in conventional horizontal clarifiers to pass liquid to be clarified through a settling zone, in which the terminal depth of clarified water at the point of collection is a function of the particle settling velocity and the upward overflow rate, to settle out the precipitates present in the liquid. The apparatus of the present invention offers a unique design which permits the liquid being clarified to travel through a settling zone having a controlled depth, along the entire length of the zone, which is a function of the particle settling velocity and the vector sum of the upward overflow rate opposed by a greater downward desludging flow rate traveling in the same direction while the precipitates are settled out. This feature permits the clarifier to attain greater flexibility in obtaining increased throughput for a given size. A more positive control and retention of the suspended or precipitated solids separated from clear effluent may also be attained with the proposed type of clarifier.
It is an object of the present invention to provide a method for removing suspended solids and the like from liquids while the liquid is flowing in a substantially horizontal direction.
It is a further object of the present invention to provide clarifier apparatus for removing suspended solids and the like from liquids which pass through the clarifier in a substantially horizontal direction.
It is another object, in accordance with the previous object, to cause the horizontal flow of liquid to define an upper free-fall layer of lower velocity and a lower sludge layer of higher velocity which approaches a point of positive separation of the clarified water above from the sludge stream below.
It is another object of the present invention to provide a horizontal flow type clarifier which provides kinetic capture of precipitates settling from an upper free-fall layer into a lower sludge layer of increasing velocity.
It is a further object of this invention to provide a horizontal flow type clarifier having a secondary clarification basin for polishing of the effluent after primary clarification.
It is yet a further object of the present invention to provide a clarifier for removing solids and the like from liquids which offers greater flexibility in obtaining increased throughout for a given size.
The above and other objects are realized in accordance with the present invention by providing a new and improved clarifier design for purifying liquids containing solids or contaminants. Briefly stated, the liquid to be purified, i.e. a liquid containing solids and the like, is fed into the clarifier apparatus of the present invention and both purified liquids and thickened solids and/or particles are produced by and discharged from the apparatus. The liquid to be treated enters the clarifier and is directed into a primary sludge contact zone where it is mixed with recirculating sludge. Chemicals may be added to the liquid in this zone to aid in the formation of precipitates. Liquid from the primary sludge contact zone is pumped via flumes to the entrance of a settling corridor for horizontal flow therethrough. The liquid flows horizontally through the corridor forming an upper free-fall zone and a lower sludge zone as the precipitates settle out. As the liquid reaches the settling corridor exit, it approaches a point of positive separation of the clarified liquid above from the sludge stream below which is formed by the kinetic capture of precipitates settling from the free-fall zone into the sludge zone of increasing velocity. The clarified liquid and the sludge stream enter a separation zone where they are caused to contact a vertical flow directing partition wall causing the sludge stream of higher velocity to pass thereunder back into the primary sludge contact zone and the clarified liquid of lower velocity to pass thereover to be boosted through flumes into a secondary settling basin for polishing. Polished liquid then flows over weirs to outlet while the sludge collected in the basin is directed to the entrance of the settling corridor.